package com.hmdp.service.impl;


import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.*;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result myQueryById(Long id) throws Exception {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);

        //互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);

        //用逻辑过期解决
        //Shop shop = queryWithLogicalExpire(id);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);//线程池

    public Shop queryWithLogicalExpire(Long id){
        //1.redis查询缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isBlank(shopJson)) {
            return null;
        }

        //判断是否过期
        //将json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime  = redisData.getExpireTime();
        if (expireTime.isAfter(LocalDateTime.now())) {
            //5.存在，返回
            return shop;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        //2.获取锁
        if(tryLock(lockKey)){
            //2.成功，开启独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(() -> {
                //重建缓存
                this.saveShop2Redis(id, 30L);
                unLock(lockKey);//释放锁
            });
        }

        return shop;
    }


    public Shop queryWithMutex(Long id) throws Exception {
        //1.redis查询缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson != null){
            return null;
        }
        //4.实现缓存重建
        //获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        if (!tryLock(lockKey)) {
            Thread.sleep(50);
            return queryWithMutex(id);
        }
        //成功，根据id查询数据库
        Shop shop = getById(id);
        //5.不存在,返回错误
        if (shop == null) {
            //数据库不存在,缓存空字符串
            stringRedisTemplate.opsForValue().set(key, "", LOGIN_CODE_TTL, TimeUnit.MINUTES);
            //不存在，返回错误
            return null;
        }
        //6.存在，写入缓存
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        unLock(lockKey);
        //8.返回
        return shop;
    }

    public Shop queryWithPassThrough(Long id){
        //1.redis查询缓存
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3.存在，直接返回
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson != null){
            return null;
        }
        //4.不存在，查询数据库
        Shop shop = getById(id);
        //5.不存在,返回错误
        if (shop == null) {
            //数据库不存在,缓存空字符串
            stringRedisTemplate.opsForValue().set(key, "", LOGIN_CODE_TTL, TimeUnit.MINUTES);
            //不存在，返回错误
            return null;
        }
        //6.存在，写入缓存
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        //7.返回
        return shop;
    }
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10L, TimeUnit.SECONDS);//尝试获取锁
        return Boolean.TRUE.equals(flag);//返回true表示获取锁成功，false表示获取锁失败
    }
    private  void unLock(String key){
        stringRedisTemplate.delete(key);//删除锁
    }
    private void saveShop2Redis(Long id,Long expireSeconds){
        //1.查询店铺数据
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(redisData));
    }
    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {
            //错误
            return Result.fail("id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否需要根据坐标查询
         if(x == null || y == null){
             //不需要坐标查询，根据类型分页查询
             Page<Shop> page = query()
                     .eq("type_id", typeId)
                     .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
             //返回数据
             return Result.ok(page.getRecords());
         }
         //计算分页参数
         int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
         int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
         //查询redis、按照距离排序、分页。结果：shopId、distance
         String key = SHOP_GEO_KEY + typeId;
//         GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
//                 key,
//                 GeoReference.fromCoordinate(x, y),
//                 new Distance(5000),
//                 RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end)
//         );

        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().radius(
                key,
                new Circle(new Point(x, y), new Distance(5000)),
                RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs().includeDistance().limit(end)
        );

        if(results == null){
             return Result.ok(Collections.emptyList());
         }
          List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
           if(list.size() <= from){
              //没有下一页了
              return Result.ok(Collections.emptyList());
          }
           List<Long> ids = new ArrayList<>(list.size());
        HashMap<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
               //获取店铺id
               String shopIdStr = result.getContent().getName();
               ids.add(Long.valueOf(shopIdStr));
               // 获取距离
               distanceMap.put(shopIdStr, result.getDistance());
           });
          String idStr = StrUtil.join(",", ids);
           List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
            for (Shop shop : shops) {
                shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
            }
            return Result.ok(shops);
    }
}
